Multi-screen displays including two or more screens in a stacked arrangement are known. An example of such a screen is disclosed in PCT/NZ98/00098. Multi-screen displays are capable of displaying image elements on multiple screens at the same time.
In practice, most multi-screen displays are dual screen displays having a front and rear screen in a stacked arrangement. At least a part of front screen must be capable of being made transparent so that images on the rear screen can be seen through it. In addition, at least a part of the front screen should be capable of becoming opaque, so that images on the rear screen could not be seen through it.
In this latter case, the inherent transparency of an LCD screen is problematic. LCD screens cannot be made to be 100% opaque. Accordingly, there will be leakage of images displayed on the rear screen through the front screen. Where image elements are displayed on more than one screen they may overlap and interfere with each other. This can be distracting.
Each pixel in an LCD screen stores values for colour and an additional value between 0 and 1 (alpha value). The alpha value determines how opaque or transparent the image element is in relation to other image elements that are displayed over the same pixels. For example, 40% alpha value for an image element will mean that it is 60% transparent (or 40% opaque).
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert and the applicant reserve the right to challenge the accuracy and relevance of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein; the reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the terms ‘comprise’, ‘comprises’ and ‘comprising’ may, under varying jurisdictions, be attributed with either an exclusive or inclusive meaning. For the purpose of this specification, and unless otherwise noted, the terms ‘comprise’, ‘comprises’ and ‘comprising’ shall have an inclusive meaning—i.e. they will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.